Question

Out of four acid derivatives only amides are least reactive. why ?

Answer 1

An amide  also known as an acid amide, is a compound with the functional groupRnE(O)xNR′2 (R and R′ refer to H or organicgroups). Most common are carboxamides(organic amides) (n = 1, E = C, x = 1), but many other important types of amides are known, including phosphoramides (n = 2, E = P, x = 1 and many related formulas) and sulfonamides(E = S, x = 2). The term amide refers both to classes of compounds and to the functional group (RnE(O)xNR′2) within those compounds.

Amide can also refer to the conjugate base of ammonia (the anion H2N−) or of an organic amine (an anion R2N−). For discussion of these "anionic amides", see Alkali metal amides.